Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] mm/hugetlb: Fix build failure with HUGETLB_PAGE but not
 HUGEBTLBFS
To:     Christophe Leroy <christophe.leroy@c-s.fr>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nishanth Aravamudan <nacc@us.ibm.com>,
        Nick Piggin <npiggin@suse.de>, Adam Litke <agl@us.ibm.com>,
        Andi Kleen <ak@suse.de>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-mm@kvack.org
References: <7e8c3a3c9a587b9cd8a2f146df32a421b961f3a2.1584432148.git.christophe.leroy@c-s.fr>
From:   Mike Kravetz <mike.kravetz@oracle.com>
Message-ID: <671b00e8-2a7a-6c19-b55b-ba2d6d0f5ad8@oracle.com>
Date:   Tue, 17 Mar 2020 10:24:49 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.5.0
MIME-Version: 1.0
In-Reply-To: <7e8c3a3c9a587b9cd8a2f146df32a421b961f3a2.1584432148.git.christophe.leroy@c-s.fr>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 3/17/20 1:04 AM, Christophe Leroy wrote:
> When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
> following build failure is encoutered:
> 
> In file included from arch/powerpc/mm/fault.c:33:0:
> ./include/linux/hugetlb.h: In function 'hstate_inode':
> ./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
>   return HUGETLBFS_SB(i->i_sb)->hstate;
>          ^
> ./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
>   return HUGETLBFS_SB(i->i_sb)->hstate;
>                               ^
> 
> Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
> Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

As hugetlb.h evolved over time, I suspect nobody imagined a configuration
with CONFIG_HUGETLB_PAGE and not CONFIG_HUGETLBFS.  This patch does address
the build issues.  So,

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

However, there are many definitions in that file not behind #ifdef
CONFIG_HUGETLBFS that make no sense unless CONFIG_HUGETLBFS is defined.
Such cleanup is way beyond the scope of this patch/effort.  I will add
it to the list of hugetlb/hugetlbfs things that can be cleaned up.
-- 
Mike Kravetz